An ogre out of a fairy tale

StoryImage( ‘/Images/Story//Auto-img-11364043415824.jpg’, ‘Microphoto by Dr. Robert A. Hedeen’, ‘The mouth is the only opening to the ant lion's digestive tract. This makes it impossible for the ant lion to defecate during its larval life.’);

One of the most ferocious monsters in the natural world, albeit a small one, is the ant lion, or doodle bug as it is sometimes called. If the creators of ogres that lay in wait for their victims in fairy tales had really wanted to scare children, they would have described the appearance and habits of the ant lion.

In the natural world, there are many ways to make a living, but some of the methods used by animals are bizarre and far stranger than fiction; such is the case of the ant lion. Who would believe that a creature could live and grow fat by merely excavating a shallow pit in sand or loose dirt and then hiding in the bottom? Yet, this is the established mode of life of this ingenious creature. Almost everyone has seen the tiny pitfalls of these interesting insects, but few know much about the animals and their modus operandi.

The ant lion is actually the larva of an insect that, in the adult stage, closely resembles a dragon or damsel fly. The “lion” is approximately one-third of an inch in length, with six legs and a small head from which extend two enormous, sickle-like jaws. The body of the bug is armed with an array of vicious spines, which adds to its overall gruesome appearance.

With an ingenious talent for civil engineering, the ant lion constructs its trap in the form of an inverted cone in sandy or dusty soil. Then, it lies in wait just under the surface of the apex of the cone for a suitable victim. It may have to wait days, or even weeks or months, before an ant or similar small creature tumbles over the edge of the pitfall. The ant lion is very patient.

When at last an ant falls in, it immediately scrambles to escape, but the shifting sand makes escape difficult. After a mad scramble, it seems almost on the verge of climbing out when the ant lion starts tossing grains of sand into the air. With sand raining down like bombs and the shifting sand below, the luckless creature usually falls to the bottom of the pit. Before it can orient itself, the ant lion attacks and pierces its victim’s body with the terrible jaws.

The jaws are really miniature hypodermic needles, and within a few seconds, the victim is killed by a powerful toxin. Not only does the poison kill the prey almost instantaneously, but it contains powerful digestive enzymes that immediately start to digest the body contents of the prey. The digestive process may take some time, but, as is usual, the ant lion is in no hurry. After a time, the internal structures of the ant are liquefied, and the ant lion begins to suck the nutritious juices from the victim through the hollow jaws into its own stomach. Eventually, all that remains of the ant is a hollow shell, which the ant lion then unceremoniously tosses from the pit and returns to its lair at the bottom of the pit to await its next meal.

The larval stage of the life cycle of the ant lion is longer than most insects because of the intermittent nature of its food supply. It usually requires two to three years to reach adulthood. When the pickings are slim in one area, it may move its trap several times to more promising areas.

Another of the “believe-it-or-not” aspects of the story of the ant lion is that there is only one opening to its digestive tract: the mouth. During its larval life in the pit, it is impossible for it to defecate.

Maybe that is why it is so mean and disagreeable?

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

From the Jan. 4-10, 2006, issue

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